Process of manufacturing pellets of explosive material.



E. DU PONI.

PROCESS OF MANUFACTURING PELLETS 0F EXPLOSIVE MATERIAL.

APPLICATION HLEIJ MAY 1. I911. nENEwEJ JAN. 1a. 1918.

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E. DU PONT.

PROCESS OF MANUFACTURING PELLETS 0F EXPLOS |VE MATERIAL. APPLICATION men MAY 1. I911- nzuzwzn JAN. I6. 1918.

1,295,975. Patented Mar. 4,1919.

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PROCESS OF MANUFACTURING PELLETS F EXPLOSIVE MATERIAL.

APPLICATION FILED MAY 1. 1912. RENEWED JAN. 16, I918.

Patented Mar. 4,1919.

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E. DU PONT.

PROCESS OF MANUFACTURING PELLETS OF EXPLOSIVE MATERIAL.

APPLICATION FILED MAY 1, 1917. RENEWED JAN. 16.!918. 1,295,975. Patented Mar. 4,1919.

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ERI TEST DU POINT, OF WILMINGTON, DELAWARE, ASSIGNOR T BALL GRAIN EXPLOSIVES COMPANY, OF WILMINGTON, DELAWARE, A CORPORATION OF DELAWARE.

PROCESS OF MANUFACTURING PELLETS OF EXPLOSIVE MATERIAL.

- Application filed May 1, 1917, Serial No. 165,671.

0 all whom it may concern,

' facturing facture of pellets of explosive material for scribed and shown.

use in the central tubes of shrapnel shells, although the invention is not limited tothis special purpose. These pellets are made in cylindrical shape and are provided with axial orifices, and are each of a size adapted to fit the central tube of a shell. Th pellets are assembled in the tubes one behind the other and act as a fuse to connect the firing means at the point of the shell with the mass of explosive material at its rear.

Difiiculty is encountered in making these pellets so that they will resist the strains, incident, to the discharge of a shell, tending to more or less crush the pellets and thus obstruct the central hole formed by the axial orifices of the string of pellets, thereby preventing the proper burning of the fuse.

The'more particular object of the invention is to so manufacture the cakes or pellets that the final product will be one in which the particles of the cake will more strongly adhere and effectively resist crushingstrains.

The carrying out of the process is not dependent upon the use of any particular apparatus, but in order to enable those skilled in the art to Garry out the process without the necessity of experiment, the mechanical instrumentalities that it is preferredto employ will be particularly de- Some of these instrumentalities are separately old, while others exhibit features ofindependent novelty.

The first step in the process is to take a quantity of grained, unglazed, explosive black powder and place it in an open-topped bowl, turning on an axis inclined to the horizontal. While the bowl is rotating, water is sprayed into its open top, preferably from an atomizer connected with a small vessel of water and with air under Specification of Letters Patent.

Patented Mar. 4, 1919.

Renewed January 16, 1918. Serial No. 212,159.

pressure. Thereby the water is distributed uniformly throughout the mass of powder. It is found that it is quite important to carefully predetermine the percentage of Water added, which should be between 1.9 and 2.1

per cent. of the powder, although a some what larger or smaller proportion of water than the range specified will give satisfactory, if inferior, results. The function of the water is to dissolve a proportion of the saltpeter of the powder and to enable the particles of powder, when subsequently molded under pressure, to stick together. The proportion of water specified is sufliciently high to attain this result but is not in excess of that required to fill the interstices or voids in the finished cake.

The molstenedpowder is then transferred to a mill in which it is ground with gasolene so as to obtain a mass containing grains of different sizes; or perhaps, more accurately, a mixture of grains and dust: the finer particles filling more or less completely the interstices between thelarger grains. The

mill preferably comprises a cylinder, re-

volving on a horizontal axis containing two heavy cylindrical rollers. The quantity of gasolene employed should be sufficient to cover the mass andrender itfluid during the process of grinding. As an example, with the grinding operation conducted at a temperature at 20 (3., approximately equal parts by weight of powder and gasolene have been found satisfactory.

After the grinding operation, the mixture may be conveyed to a vessel containing a rotary stirrer, which is continuously operated to prevent settling and maintain the powder in suspension in the gasolene. Thence the mixture is conveyedinto a main supply pipe, from which branch other pipes, controlled by valves, leading to individual molds. A number of these pipes may be operated in unison so as to simultaneously fill a series of molds. 1

The molds are of cylindrical shape and a fixed in extends through the axis of each mold, this pin forming the central hole in the finished cake or pellet. The bottom of the mold is a movable plunger which, when depressed to allow the inflow of the mixed gasolene and powder, forms a moldpf much greater height than the length of thefinfilled with the mixture,

a shutter, and by hydraulic power thev ished pellet. The mold, after it is entirelyclosed at the top by plunger is moved up while 'theshutter is.

pressed down. The gasolene, or the larger part thereof, is forced out between the in-j ner wall of the mold and the plunger and the powder is compacted into a mass of the desired density. The How of water to each hydraulic cylinder actuating the corre-. sponding mold plunger is controlled by a check valve, so as to effect a slow movement of the plunger on its compression stroke,

thus giving ample time for the escape of the gasolene and avoiding the possibility of explosion, and also allowing a quick return of the plunger. Before the ejection of the pellet from the mold, the saine is held under pressure for a time to produce the de-' sired degree of hardness in the pellet. The

,and the plunger mlne the quantity of powder in each pellet.

By means of the conveyer, the pellets are carried through a dry-house, which is heated to a temperature of, referably, about 100 degrees centigrade an a properly ventil'ated. a

' While I have specified and claimed the grinding of the moistened granular powder 1n gasolene, it will be understood that I 1ntend to comprehend the use of any liquid which, for the purposes of my process, is an equivalent. Any liquid which has little or no solvent or chemical action upon the powder ingredients and which will not render the grinding operation unsafe and which is not miscible with water and does not disturb the fixed relationship of the powder to the moisture may be substituted.

The apparatus hereinbefore described in general terms is shown in the drawings, in which Figure 1 is a sectional view illustrating the apparatus for. carrying on the first step in the process, that is moistening the explos1ve.

grinding apparatus.

of the machine for compressing the explosive mixture into pellets, together with the hydraulic connections and operating valves.

Fig.4 is a side view of one of the compressing machines, principally in central section, together with the arrangement for.

' feeding the mixture and carrying off. the

pellets.

Fig. 5 is a detail sectional view of one of the compressing plunger-s.

'Fig. 6 is a diagrammatic plan view of a Fig. 2 is a similar view illustrating the normally held closed Fig. 3 is a front. view, partly in section,:

gang of compressing machines with the hy draulic connections and the feed lines from the stirrin tank.

Fig. 7 shows the stirring tank in vertical section.

Fig. 8 is a perspective view of a portion of the dry-house. 1

Fig. 9 shows one of the finished pellets.

The device for moistening the explosive, thoroughly comprises an open bowl 0. carried on a shaft I) mounted in bearings at an angle of approximately to the horizontal. Shaft 12 is shown as rotated by bevel gears c from a horizontal shaft d. A small vessel e, for the water, is mounted on' some stationary support'f' adjacent to the opening in bowl a. Vessel -e is provided With an air pressure pipe g and an atomizing nozzle h for spraying. the water into the opening in the bowl.

The thoroughlymoistened explosive is then placed in the barrel 71 together with gasolene. Barrel 7 is caused to rotate upon rollers j,and carries within it two cylindrical rolls In, which-by theirown weight crush the powder grains when the barrel .is r0- tated. This apparatus is similar to that used Oflice December 13,1913, whereby powder grains are crushed to a owder.

In the present inventlon, this step in the process is carried on only to a limited extent 'until .suiiicient of the powder grains have been pulverized to fill in the interstices be- I tween the remaining uncrushed grains. 1

Themixture of gasolene and crushed and uncrushed powder grains is then transferred to a stirringtank Z shown in Figs. 6 and The contents of this tank are kept agitated by means of a beater m rotated by gearing indicated at 11,, thus keeping the powder 1n a state of suspension in the gasoene. A feed main 0 leads from the bottoniof tank 1 to a line running in proximity to a gang of presses,'and thence back to tank Z, discharging the overflow into said tank. A pump p in feed main o-keeps up this circu lation. f

A short passage 9 leads from main 0 to the mold 1- of each press, and a valve .9 which controls the flow through each passage q is by a. spring t and is opened by means of a leveru. Lever u for feeding the mold of each press is actuated by a cam a) mounted on a common shaft w. Thus byturning the shaft 20, all the molds may abe fed and the quantity fed to each determined. a L

The seat for valve 8 is placed directly at the junction of passage g with feed .main 0,

in an invention filed by me in the Patent thus leaving no dead space behind the valve wherein the mixture might settle and prevent its opening.

' The castlng forming the housing 21 for "be stopped by the end wall of the housing and fall again into passage 9. I Y

Each press comprises a fixed vertical mold 10, the top of which is closed by a sliding shutter 11, and the bottom of which is formed by the plunger 12.

Plunger 12 is actuated as follows: Above and in line with mold 10 is a hydraulic cylinder 13 with a piston 14 whose rod 15 passes through the upper end of the cylinder and through a fixe bearing guide 16. Above the cylinder, rod 15 carries a yoke frame 17, the ,side rods 18 of which pass downward through bearings on either side of mold 10, and which on its lower cross piece carries the centrally'located plunger 12 in sliding relation with mold 10. Cylinder 13 is carrled on a post 19 which has a slight vertical movement in a bearing 20 fixed to the frame of the machine. Below this bearing, post 19 I has an extension 21 which reaches down to shutter 11. Extension 21 is bifurcated and its two feet are grooved as at 22, the sides of the grooves forming a guide-way for the shutter 11, and the tops of the grooves abutting upon the top of the shutter when post 19 is pressed downward n lt s bearing 20.

By this arrangement, it Wlll be seen that when piston 14 is pressed upward, yoke 17 will be forced up and with it plunger 12, compressing the contents of the mold 10 against shutter 11. At the .same time, cylinder 13 will be pressed downward until extension 21 abuts upon shutter 11 and holds it down over the top of the mold. Thus, no matter what pressure is used to compress the mixture in the mold by forcmg up plunger 12, exactly the same pressure 15 acting to keep the top of the mold closed against it.

The bifurcation of extension 21 allows the end of passage 9 to enter and deliver the mixture directly into the top of the mold when the shutter 11 is open. Shutter 11 1s slidably actuated to open or close the top of the mold by means of a bell crank 23; a pm 24 in one arm of said bell crank loosely engages in a hole in the shutter, and a hole 1n the other arm of said bell crank loosely engages a pin 25 attached to aslidable rod 26. It will be understood there is a bell crank 23 for each press, andthat rod 26 extends along in front of the gang, of presses, and 1s longitudinally movable to open or shut the shutters on all the presses in the gang at Once.

Plunger 12 is hollow and a fixed rod 27,

supported by a bracket 28, below yoke 17, passes up through said yoke, through the plunger and through the mold to the top thereof. This rod 27 forms the longitudinal hole in the pressed pellets. Plunger 12 is cut away, exteriorly and interiorly for most of its length, but at the top for a short distance at'29 it fits the mold fairly, and also the central rod 27,80 that none of the powder in the mixture may pass in the pressing operation, but allowing the fluids to slip by. The fluid thus expressed, and any that may leak out from beneath the shutter 11, is collected in suitablecans 30 and may be used over again in the grinding process.

The cylinders of the presses receivehydraulic pressure through mains 31, 32, which are controlled by 4-Way valve 33. As shown in Fig. 3, hydraulic pressure 1s admitted through pipe 34 from a source not shown, passes through valve 33 into main 31, whence it is led by short connection 36 to the bottom of each cylinder 13. As the piston is thus forced up, the fluid above it escapes by Way of connection 37 to main 32,

When the pressure has been on sufliciently to form the pellet in the mold, 'valve 33 is turned 90 until its handle 40 reaches the broken line position in the figure. This reverses the hydraulic flow, and as check valve 38 opens freel in this direction, piston 14 and plunger 12 escend rapidly.

According to the plan illustrated in Fig. 6, the. presses are arranged in two gangs, each gang being operated by a 4way valve 33, the two valves beingplaced near each other. In this way an operator may stand midway in the lineof presses and operate one of said valves to make one-half the presses active while the other valve is turned so thatthe other half of the presses are discharging. He may then turn both valves and reverse the operation inboth of the sets of presses. In this way he is enabled to Ill use only one-half the hydraulic'power'and instead of.

rod 26 is operated to open all the shutters. Pressure is then again applied and plunger 12 is raised to the top of the mold ejecting the pellet. Then the 4-Way valve is reversed to the exhaust position as described above.

First, however, rod 26 may be again operated, closing shutters 11, which push the ejected pellets into chutes 41 leading through the backs of the presses into a conveyer 42,

running in a'trough 43.

During the lowering movement of plungers 12, shaft w is operated to open valves 8 and mixture is fed through passage 9 and delivered into the mouth of the mold. The drawing down of plunger 12 aids in this filling of the mold by sucking the mixture in after it.

The finished .pellets, see Fig. 9, are carried by the conveyer 42 to a dry-house 44, shown in Fig. 8. The dry-house is not wide, low, but of extreme length, and is provided with heating pipes 45, and with side rollers 46, upon which trays 47 of pellets may be slid in, and one behind another push each other through the dry-house. The ends remain open, and the progress of the pans of pellets through the dry-house is so slow as to thoroughly and completely remove all moisture from thepellets. Moreover, this is accomplished with a minimum of risk of explosion, as the heat given off by pipes 45 need not be excessive, and also the powder pellets being strung along in the comparatively small trays 47, present no great amount of the explosive at any one place.

Having now fully described my invention, what I desire to claim and protect by Letters Patent is:

1. The process of makingexplosive material, which consists in moistening unglazed explosive black powder, grinding the same to obtain a mixture of grain and dust, and then molding the same.

2. The process of making pellets of explosive material, which consists in moistening unglazed explosive black powder, grinding the same to obtain a mass of difl'erent sized grains, and molding the same under pressure.

'- 3. The process of making pellets of explosive material, which consists in moistening grained unglazed black explosive powder, grinding the same in gasolene, and

v molding the explosive into pellets.

4. The process which comprises evenly moistening grained unglazed explosive black powder with a proximately two per cent. of water and su sequently forming the explosives into pellets, the moistening operation dissolving a proportion of the saltpeter and causlng the particles of the pellets to adhere together and resist crushing strains.

5. The process lof making pellets of explosive material, which consists in moistenvery ,der with approximately two per cent. of water, grinding the moistened powder in gasolene to obtain a mass of different sized K grains, and molding --the explosive into pellet 6. The process of making pellets of explosive material, which consists in agitating a mass of grained unglazed black powder and simultaneously spraying the same With water in a finely divided state to effect a uniform moistening of the mass, grinding the moistened powder, and molding the explosive into pellets.

7. The process of making pellets of explosive material, which consists in subjecting a mass of grained unglazed black powder to a rotary tumbling action and simultaneously spraying the same with Water in a finely divided state, grinding the moistened powder, and molding the explosive into pellets.

8. The process of making pellets of explosive material, which consists in moistening grained unglazed black explosive powder, grinding the moistened powder in a quantity of gasolene sufficient to render it fluid, flowing the mixture into molds, and subjecting it to pressure to expel a substantial part of the gasoleneand mold the pellets.

9. The process of making pellets of explosive material, which consists in moistening grainedunglazed black explosive powder, grinding the same .in gasolene, flowing the gasolene and powder into a mold, subjecting the same to pressure while expelling a substantial portion of the gasolene, and maintaining the pressure to produce the desired degree of hardness of the pellets.

10. The process of making pellets of explosive material, which consists in uniformly moistening a mass ofgrained unglazed explosive black powder, grinding the same in gasolene to obtain amass of different sized grains, molding the explosive under pressure while expelling a substantial part of the gasolene, and drying the molded pellets.

11. The process of making pellets of explosive material, which consists in moistening grained unglazed explosive powder, grinding the same in gasolene, molding the explosive into pellets, and subjecting the pellets to a temperature of approximatelv 100 degrees centigrade. U

'12 The process of making pellets of explosive material, which consists in moistenlng grained unglazed black explosivepowder, grinding the same in gasolene, transferring the mixture of gasolene and powder to a mold and regulating the proportions therein of gasolene and powder to predeter- Inine the size and weight of the finished pellet, and molding the explosive into pellets.

13. The process of making pellets of explosive material, which consists in moistening a mass of grained unglazed explosive black powder, grinding the same in gasolene to obtain a mass of different sized grains, the quantity of gasolene being sufiicient to render the mixture fluid, agitating the mixture after grinding to prevent settlement, flowing the mixture into molds, subjecting the mixture to pressure to expel a substantial part of the gasolene and mold the powder into pellets, and drying the 10 molded pellets. k

In testimony of which invention, I have hereunto set my hand, at Wilmington, Del., on this 28th day of April, 1917.

ERNEST DU PONT. 

